Nanoscale materials and devices have proven to vastly improve upon a wide range of industries with significantly increased performance and novel functions. Moreover, metamaterials, films, materials, and devices fabricated on a flexible substrate have shown extreme promise due to their low weight, mechanical flexibility and durability, with a low projected cost and large area processing, especially when comparing flexible electronic devices to their traditional, silicon wafer based counterparts. Devices with applications ranging from water purification, wearable sensor arrays, displays, batteries, photovoltaic cells and supercapacitors in a multitude of industries such as healthcare, transportation, energy, mobile devices, and embedded systems are found to have improved performance at lower cost when compared to traditional microscale electronics. The same can be said for a plethora of photonic films, metamaterials, and other products based upon flexible, nanostructured patterns. The proliferation of these promising devices will bring truly enormous benefit to society.
However, one of the barriers to the widespread adoption of this methodology is the challenge in transitioning from small research-scale fabrication to large volume production. This issue is rooted in two conditions necessary for the viability of a new technology. First, the yield of the production must be high enough to justify mass manufacturing cost and second, the capital development costs to transition from prototype to volume-scale manufacturing must not exceed potential gains. These factors are highly dependent on the ability to conduct fast and accurate metrology. Implementation of production speed, in-line, direct metrology with nanoscale resolution represents a marked increase in feedback for the purposes of, among others, process control and yield enhancement.
A barrier to consumer-grade and volume-scale adoption of these types of products is the difficulty in accurately measuring fabricated structures on the nano-scale and conducting effective defect detection. The ability to conduct fast and accurate in-line metrology is critical to pushing yields high enough to justify manufacturing and R&D costs.
This growing need for accurate measurement and evaluation of fabricated nano-structures has led to widespread use of scanning probe microscope, including atomic force microscopy (AFM), in a variety of industrial and research settings. Almost all current direct measurement instruments, such as AFMs, require the use of extremely expensive and delicate optical and motion equipment. While very accurate, traditional implementations seen in widely available commercial products are not compact and require a significant amount of specialized and bulky systems, which makes it ill-suited for high-throughput, in-line measurement applications. For instance, in the fabrication of semiconductor devices, wafers will periodically be taken out of the assembly line and imaged with a large, bench scale or room scale AFM system to ensure fabrication has occurred within the optimal parameters for meeting critical dimensions and defect levels. However, the majority of these systems are relatively slow to scan and can only measure a single area of a less than a square millimeter. This makes it very difficult to extrapolate larger conclusions about the centimeter or meter scale sample from just a single scan, necessitating multiple “step-and-scans” and thus further decreasing throughput. As any nanofabrication or nanosculpting process will experience variation over a large working substrate, and certain metrology marks and structures in “hotspots” strategically spaced across the working substrate, usually on the millimeter or centimeter scale, help extrapolate the larger picture of fabrication quality while measuring all these hotspots quickly and accurately. Moreover, even in the small number of products that utilize multiple AFM tips to image a sample, they are arranged in a tight array with tip spacing usually on the microscale and all sharing a common ground structure to which the fixed end of the AFM cantilever is attached. which makes processing on non-planar or non-rigid samples a near impossibility and severely limits hotspot scanning throughput. Further, due to the difficult in quickly (e.g. without limiting production throughput of the R2R process) and precisely measuring nanostructures on a flexible substrate, in flexible, roll-to-roll (R2R) processes manufacturers are typically limited to the information provided by indirect, primarily optical, measurement techniques which lack the ability to quantify individual critical features or dimensions.
Therefore, what are needed are devices, systems and methods that overcome challenges in the present art, some of which are described above.